Swiftwater, Pennsylvania (CNN) -- Vaccine manufacturing giant Sanofi Pasteur opened its doors to the media Wednesday, inviting reporters to a first-of-its-kind, up-close look at its H1N1 flu vaccine production facility.

Sanofi, the only manufacturer licensed to make H1N1 vaccine in the United States, also released its final clinical trial data, a 42-day follow-up of its adult and pediatric trials. According to this latest data, a single dose of H1N1 vaccine induces a strong immune response in adults, but two doses will be needed for children 6 months to 9 years of age.

"These are extremely important data," said Wayne Pisano, president and CEO of Sanofi Pasteur, "because they once again make clear not only the immunogenicity of Influenza A [H1N1] 2009 Monovalent Vaccine manufactured by Sanofi Pasteur, but also the fact that this vaccine has a safety profile similar to that observed with seasonal influenza vaccine in all age groups studied."

According to Sanofi, there were no serious adverse incidents associated with vaccination.

While no cameras were allowed inside the production facility during the tour, journalists were taken through the bulk influenza vaccine manufacturing facility, where the virus is injected into eggs to produce vaccine; the quality contol and sterility lab, where safety testing is done; and the formulation and filling facility, where single dose syringes and multidose vials are filled.

In response to questions about criticisms over a shortage of vaccine, Chris Viehbacher, CEO of parent company Sanofi Aventis, said he has 2,000 employees on-site 24 hours a day, seven days a week. Viehbacher said the facility is producing 5 million doses a week, and that will increase to between 9 million and 10 million by early December.

By the end of this week, Sanofi will have shipped 20 million doses of H1N1 vaccine, according to the company.

According to Viehbacher, Sanofi will be on target to ship the entire 75 million doses ordered by the U.S. Department of Health and Human Services by the end of the year.

"We are all working as fast as we can," Viehbacher said. "Everyone would like to have more vaccine now but we have what we have. Those not at risk should have some degree of patience."

Sanofi also will deliver 50 million doses of seasonal flu vaccine before the end of the month, the company said.

By the end of the year, "125 million doses of both vaccines [seasonal and H1N1] will be out the door," Viehbacher said.

He added that it is important to understand that 85 percent of the manufacturing process is testing and quality control, not growing the vaccine.

Sanofi, the largest vaccine company in the world, makes more than 45 percent of the flu vaccine distributed in the United States and about 40 percent of the world's supply.